Adirondack Mountains

The Adirondack Mountains/ædɪˈrɒndæk/ form a massif in northeastern New York, United States. Its boundaries correspond to the boundaries of Adirondack Park. The mountains form a roughly circular dome, about 160 miles (260 km) in diameter and about 1 mile (1,600 m) high. The current relief owes much to glaciation.

Map of the main mountainous regions of the northeastern United States. Strictly speaking, neither the Adirondacks nor the Catskills and Poconos are part of the Appalachian Mountains, having much different origins.

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1876 map of the Adirondacks, showing many of the now obsolete names for many of the peaks, lakes, and communities.

The earliest written use of the name, spelled Rontaks, was in 1729 by the French missionary Joseph-François Lafitau. He defined it as tree eaters. In the Mohawk language, Adirondack means porcupine, an animal that may eat bark. The Mohawks had no written language at the time so the Europeans used various phonetic spellings. An English map from 1761 labels it simply Deer Hunting Country and the mountains were named Adirondacks in 1837 by Ebenezer Emmons.[1]

In 1664 the land came under the control of the English when New Netherland was ceded to The Crown. After the American Revolutionary War, the lands passed to the people of New York State. Needing money to discharge war debts, the new government sold nearly all the original public acreage about 7 million acres for pennies an acre. Lumbermen were welcomed to the interior, with few restraints,[3] resulting in massive deforestation.

Note that even though they all resulted from the Grenville orogeny, neither the Adirondacks (now uplifted by a hot spot) nor the Catskills or Poconos (a dissected plateau formed from delta deposits) are part of the Appalachian Mountain chain (faulted and folded by continental collisions).

Around 600 million years ago, as Laurentia drifted away from Baltica (European Craton), the area began to be pulled apart forming the Iapetus Ocean. Faults developed, running north to northeast which formed valleys and deep lakes. Examples visible today include the grabensLake George and Schroon Lake. By this time the Grenville mountains had been eroded away and the area was covered by a shallow sea. Several thousand feet of sediment accumulated on the sea bed. Trilobites were the principal life-form of the sea bed, and fossil tracks can be seen in the Potsdam sandstone floor of the Paul Smiths Visitor Interpretive Center.[6]

About 10 million years ago the region began to be uplifted. It has been lifted about 7000 feet (ca. 2,134 meters) and is continuing at about 2 millimeters per year, which is greater than the rate of denudation. The cause of the uplift is unknown, but geologists theorize that it is caused by a hot spot in the earth's crust.[6] A recent study has revealed a column of seismically slow materials about 50-80 km deep beneath the Adirondack Mountains[7], which was interpreted to be the upwelling asthenosphere contributing to the uplift of the mountains. The occurrence of earthquake swarms near the center of the massif at Blue Mountain Lake may be evidence of this. Some of the earthquakes have exceeded 5 on the Richter magnitude scale.

Starting about 2.5 million years ago a cycle of Pleistoceneglacial and interglacial periods began which covered the area in ice. During the most recent episode, the Laurentide Ice Sheet covered most of northern North America between about 95,000 and c. 20,000 years ago.[8] After this the climate warmed, but it took nearly 10,000 years for 10,000 feet (ca. 3,048 m) thick layer of ice to completely melt. Evidence of this period includes:

The Adirondack Mountains form the southernmost part of the Eastern forest-boreal transitionecoregion.[10] They are heavily forested, and contain one of the southernmost distribution taiga in North America. The forests of the Adirondacks include spruce, pine and deciduous trees. Lumbering, once an important industry, has been much restricted by the creation of the park.[11]

The mountains include many wetlands, of which there are three kinds:[6]

Nearly 60 percent of the park is covered with northern hardwood forest. Above 2600 feet (ca. 792 meters) conditions are too poor for hardwoods to thrive, and these trees become mixed with or replaced by balsam fir and red spruce. Above 3500 feet (ca. 1,067 meters) black spruce replace red. Higher still only trees short enough to be covered in snow during the winter can survive.